This invention relates to the field of formatting handwritten data displayed on computer systems.
A typical computer system may include a central processing unit (CPU), main memory such as random access memory (RAM), a data entry device including a positioning device, a mass storage device such as one or more disk drives, a display and/or a printer. In previously known computers, the data entry device often consists of a keyboard, on which a user enters data by typing. The positioning device of a previously known computer system may have consisted of a "mouse" or other cursor positioning device.
The positioning of typewritten characters or words on a computer display is a common operation for previously known computers. This positioning is usually done using the baseline of a character or word. A baseline is the horizontal line on which text characters or words "hang." By knowing the baseline of a character or word the computer can correctly position the character or word relative to other characters or words. In previously known devices the baseline information about each character is usually stored in computer memory.
Computer systems have also developed that can accept handwritten data entry rather than keyboard data entry. These systems are often characterized by the use of a pen, stylus, or other writing device, to enter handwritten data directly on the display of the computer system. Alternatively, these systems may provide for a user to enter data on a digitizing tablet or other input device, with the image of the written input displayed on a separate computer display output device. The writing device for entering handwritten or freestyle stroke input information is not limited to a pen or stylus, but may be any input device such as a mouse, trackball, pointer, or even a user's fingers. Such systems are not necessarily limited to receiving data generated by human users; for example, machine generated data may also be inputted into and accepted by such systems.
Computers in one class of handwriting entry computer systems are referred to as "pen-based" computers. In a pen-based computer system, a writer can input information on a display by "writing" directly on the display. A writing device, such as a pen or stylus, is used to enter information on the display. In a typical pen-based computer system, a user touches the stylus to the display and writes as he or she would on a piece of paper, by making a series of pen strokes to form letters or words. A line appears on the display that follows the path of travel of the pen point so that the pen strokes appear on the display just as ink would appear on a handwritten page. Thus the user can enter information into the computer by writing on the display. Pen-based computers typically have a display surface that serves as both an input receiving device and as an output display device.
A disadvantage with pen-based computer systems is the proper formatting of handwritten information. Specifically, these systems have difficulty accurately positioning handwritten characters or words relative to each other. This is because, as with unlined paper, it is often hard for a user to write in a straight line. Furthermore, unlike typewritten characters or words, where the computer inherently knows the baseline, pen-based computers systems do not know the baseline of the handwritten characters or words. This is because every time a person handwrites a character or word it may appear differently and thus the baseline may be different. Also, the computer may not immediately attempt to perform character recognition and may thus not even know what the character or word is supposed to be. Moreover a person may not properly align all of the characters in a word. The result is that computer systems that accept handwritten data entry have not been able to accurately position and display handwritten words or characters in a straight line.
This becomes even more of a problem when a user performs operations such as inserting and deleting handwritten characters or words. In these situations the computer has no way of knowing how to position inserted words or characters relative to existing words or characters and has no way of knowing how to reposition existing words or characters when other words or characters have been deleted.
One previously known solution to this problem is for the computer system to supply the user with a line to write the handwritten words, much like one would write on ruled paper. The problem with that system is that it relies on the user to write on the line. If the user ignores the line, the handwritten text will not be positioned properly. Furthermore, if the user decides to insert handwritten text in the middle of a line of handwritten text, unless a space on the line is made for this new text, the computer cannot determine what the baseline of the inserted word is.
It would be desirable to identify a positional guideline, such as a baseline or ascender line, of handwritten data. This positional guideline could then be used to accurately position handwritten data on a computer display and would further allow for easy insertion and deletion of handwritten data. The guideline could also be used to change the appearance of handwritten data--such as by italicizing.